<!DOCTYPE html>
<html ng-app="">
<head>
    <meta charset="UTF-8">
    <title></title>
    <script src="angular/angular.min.js"></script>
</head>
<body>

Your name: <input type="text" ng-model="yourname" placeholder="World">
<hr>
Hello {{yourname || 'World'}}!

</body>
</html>